The key to maintaining the long-term
viability of any activity or condition is the concept of sustainability.
Protecting the Grand Canyon river experience and the future of guiding
is no exception. To assure that our children and future generations will
have the same opportunities and quality of experience is dependent on
our ability to create a sustainable management program for the Colorado
River. The quality of the experience of the future is fully dependent
on maintaining the quality of the place that provides the experience.
The way that the Colorado River is currently managed is clearly not sustainable.
Without a doubt the single greatest threat to the future of the Colorado
River corridor in the Grand Canyon is the presence of Glen Canyon Dam.
If we only look at river protection with a short-term view it is easy
to make a case for maintaining the status quo regarding Glen Canyon Dam.
The regulated flows from the dam create a degree of certainty upon which
to plan and execute commercial river trips. In addition, there is a powerful
urge in the human psyche to maintain a status quo that is perceived to
be beneficial at the time. Change on the other hand takes effort and involves
risk or even personal sacrifice. The status quo is always the path of
least resistance but it is not necessarily the best or wisest path. The
path of least resistance is to the left at Bedrock, but do you want to
go there?
Supporting the continued operation of Glen Canyon Dam is a path that will
eventually lead to disaster, just as sure as running left in Crystal at
50,000 cfs. It is becoming very clear that the construction of this dam
was a huge mistake because it has created a situation that is not sustainable.
The most obvious and unavoidable problem is the accumulation of sediment
in the reservoir. It must be clearly understood that the primary natural
function of the Colorado River is to transport the easily eroded soft
sandstone of the Colorado Plateau to the sea. The forces of erosion and
gravity cannot be denied. Within the scope of geologic time, this process
is less than half completed. There is still enough sediment to be transported
by the river to fill both Powell and Mead reservoirs thousands of times
over. Sediment accumulation alone will eventually led to failure of the
dam and subsequent unprecedented damage to the Grand Canyon and other
resources downstream.
The huge sediment load carried by the Colorado River has been a known
fact since the earliest river explorations. It is a tragedy that in 1954
Congress knowingly failed to adequately consider the seriousness of this
problem. It is a little understood fact that one of the primary political
reasons for building Glen Canyon Dam was to prolong the life of Hoover
Dam and Lake Mead. In the years following the construction of Hoover Dam
the rate of sediment accumulation in Lake Mead was alarming. It was clear
that unless the huge annual sediment load of the Colorado River was trapped
somewhere else upstream the life of Hoover Dam was limited. As is often
the case, relatively short-term economic needs won the day and Congress
authorized Glen Canyon Dam. Some future Congress would have to deal with
the consequences.
In addition to serving as a sediment trap, the dam produced power generation
revenue that the upper basin states used to construct more dams and diversions
on the tributaries of the Colorado. This purpose has been fulfilled. Now
society is faced with paying the price. Dealing with sediment accumulation
in the reservoir, and paying for the huge losses of water that evaporate
in periods of drought, will eventually cost far more than the initial
economic benefits provided to the upper basin states. Time will prove
that it would have been far less expensive just to have used tax dollars
to pay for these upper basin storage projects and let the river run free
through Glen and Grand Canyons.
In addition to escalating economic losses as a result of the dam, most
boatmen are well aware of the severe ecological damage created both upstream
and downstream of this dam. The National Park Service (nps) is responsible
for protecting and managing the resources found within most of the Colorado
River system north of Hoover Dam. The nps has a congressional mandate
to protect park resources and natural processes “unimpaired for
the enjoyment of future generations.” The body of law that creates
this mandate is just as relevant to our culture as that which pertains
to the management of water and power. The chronic impairment of the aquatic
ecosystem of the Colorado River is well documented. In response to growing
public concern over the adverse effects of the operation of Glen Canyon
Dam on the resources of the Grand Canyon, Congress passed the 1992 Grand
Canyon Protection Act. This act directed the Secretary of the Interior
to mitigate the negative effects of the dam on downstream resources. An
Environmental Impact Study (eis) was conducted and a Record of Decision
(rod) was signed in 1996. The Glen Canyon Dam Adaptive Management Work
Group (amwg) was established to advise the Secretary on dam operational
changes authorized within the rod and to report on progress made in the
mitigation progress.
An impressive amount of research and monitoring has been conducted in
support of this effort. Beginning with the Glen Canyon Environmental Studies
program which gathered information for the eis, and continuing with the
Grand Canyon Monitoring and Research Center supporting the amwg, over
a decade of research and associated experimental flows has been conducted
costing taxpayers over eighty million dollars. Although much has been
learned, very little progress, if any, has been made in actually reducing
the impacts. The total demise of the natural biodiversity of the Colorado
River ecosystem within the Grand Canyon is nearing completion. It is becoming
increasingly clear that altering dam operations will not be effective
in mitigating ecosystem changes brought about by the presence of the dam.
Although the current damages to Grand Canyon resources are tragic, future
catastrophic events brought about by the accumulation of river sediment
in the reservoir will be devastating.

Since the completion of Glen
Canyon Dam in 1964, the Colorado’s nearly one hundred million ton
average annual sediment load has been collecting in Lake Powell. It is
an undisputed fact that unless a very costly annual dredging program is
commenced soon, or the dam is decommissioned and a river bypass created,
Lake Powell will fill with sediment.
However, well before the entire lake is filled with silt, the advancing
sediment toe will first clog the dam’s river outlet works, the only
openings that can be used to release water in times of low reservoir levels.
Located at elevation 3374 (one hundred feet below the generator penstock
openings), Bureau of Reclamation (bor) data estimates that sediment will
clog these openings in about another eighty years (E. Shultz, 1961). In
times of prolonged drought, if the reservoir level drops to elevation
3490 (within twenty feet of the center of the generator penstock openings),
the generators must be shut down. If the existing drought continues, it
is possible that this could occur within two years. In this event the
outlet works will be used to bypass the generators in order to deliver
the minimum flows required by law through the dam. No electric power would
be generated until the lake level rose back above the penstock intake
openings, which could be several years. This event, in itself, might not
be more harmful to the canyon, but the scenario gets worse. Now fast-forward
eighty years into the future. The outlet works are now clogged with sediment
and the same drought scenario occurs. When the lake level drops below
the penstock openings there is no longer any way to release water from
the dam. Except for the inflows from the few small tributary streams within
the Grand Canyon, the flow of the mighty Colorado will be a reduced to
mere trickle.
As the sediment level continues to deepen it will reach the penstock openings
in another fifty years. Unless there is a way to raise these openings
higher on the face of the dam, there will no longer be any way to release
water at any reservoir level. In wet cycles, because of drastically reduced
reservoir storage capacity, the water level could easily reach the spillways.
These spillways were not designed for the discharge of water for prolonged
periods of time. High volume use of these spillways for more than a week
or two would most likely lead to their catastrophic failure.
According to bor studies, over-topping of the dam would likely lead to
the formation of a river channel through the soft sandstone on either
side of the dam. Considering the tremendous water pressure created by
a reservoir of this size and the easily eroded sandstone that abuts the
dam, once the spillways failed, complete breaching of the dam could occur
in a matter of hours. Such an event would be devastating to the inner
gorge of the Grand Canyon. Following the near failure of the dam in 1983,
the Bureau of Reclamation prepared a flood inundation model for the failure
of Glen Canyon Dam (S. Latham, bor 1990). According to this study, in
the event of overtopping or breaching of the dam the crest of the flood
would be over five hundred feet high when it reached the Grand Canyon
and 230 feet high when it reached Lake Mead. The study concludes: “
The failure of Glen Canyon Dam due to overtopping would produce catastrophic
flooding with unprecedented flood depths and discharges all the way to
Lake Mead and Hoover Dam. Even if Hoover Dam did not fail, there would
be unprecedented flooding downstream of Lake Mead as well”.
Although the recent drought period precludes such an event occurring in
the near term, the exposed sediment bed at the upper end of Lake Powell
is a vivid reminder that the sedimentation process is well underway. The
time to act is now before the situation becomes unmanageable. If dredging
is to be the long-term solution, it must start immediately while the advancing
sediment toe is still near the road access at Hite. If engineering studies
prove that annual dredging will be too costly and impractical in this
remote location, the nps and Congress should aggressively seek the decommissioning
of Glen Canyon Dam. With a dam bypass the accumulated sediment can be
carried naturally through the Grand Canyon over a period of years where
it can be more easily dredged and removed at Lake Mead.
Although the legal and policy ramifications of this issue are complex
and politically sensitive, there is compelling evidence that there would
be both short and long-term positive economic benefits from restoring
a free flowing river through Glen and Grand Canyon. The government could
then focus its effort on managing Lake Mead as a sustainable water storage
and hydropower facility. Resolving this critical problem will take courage
and strong commitment to creating a sustainable future for the unique
aquatic ecosystem of the Grand Canyon, Colorado Rivers water users, and
Grand Canyon boatmen yet to be born.